Arguments

From what I've seen, he is very similar to Trump: very little in terms of ideas, a lot in terms of emotions and controversial publicity. His appeal is mostly based on him posing as an outsider (which he actually is not) and denouncing the ruling class. Whenever he talks about policies, he uses very vague and ambiguous terms, from which it is impossible to discern what he is actually planning to do.

The Brazilian political system is extremely corrupt, so a straightforward populist becoming the president is a bad sign. On the other hand, Brazil has had a series of horrible presidents implementing countless socialist policies that have bankrupt the country, so someone who, for the first time in decades, openly vows to clean them out could be a welcome change.

I doubt life in Brazil will become much better any time soon; the system is too broken, and the society is too beaten up, to be able to accomplish anything in the short run. That said, the nearby Venezuela being in the state it is has a potential to scare people enough to denounce statism en masse - and that can have very positive long-term consequences. Brazil definitely has a lot of potential, it just needs a strong push to get started.